Varicose veins associated with DVT incidence

Adults who were diagnosed with varicose veins have a significantly increased risk of incident deep venous thrombosis (DVT), although whether the association between varicose veins and DVT is causal or represents a common set of risk factors requires further research. The study researchers led by Dr Shyue-Luen Chang from Chang Gung Memorial Hospital, Taoyuan, Taiwan, said that the findings for pulmonary embolism (PE) and peripheral artery disease (PAD) are less clear due to the potential for confounding.

The paper, ‘Association of Varicose Veins With Incident Venous Thromboembolism and Peripheral Artery Disease’, published Journal of the American Medical Association, investigated whether varicose veins are associated with an increased risk of DVT, PE or PAD.

For this retrospective cohort study, the researchers used claims data from Taiwan’s National Health Insurance programme. Patients aged 20 years and older with varicose veins were enrolled from January 2001 to December 2013 and a control group of patients without varicose veins were matched by propensity score. Patients previously diagnosed with DVT, PE, or PAD were excluded.

Outcomes

In total, 212,984 patients were assigned to the varicose veins group (mean [SD] age, 54.5 [16.0] years; 69.3% women) and 212,984 to the control group (mean [SD] age, 54.3 [15.6] years; 70.3% women). The median follow-up duration was 7.5 years for DVT, 7.8 years for PE and 7.3 years for PAD for patients with varicose veins, and for the control group, follow-up duration was 7.6 years for DVT, 7.7 years for PE, and 7.4 years for PAD.

The varicose veins group had higher incidence rates than the control group for DVT (6.55 vs 1.23 per 1,000 person-years [10,360 vs 1,980 cases]; absolute risk difference [ARD], 5.32 [95% CI, 5.18-5.46]), for PE (0.48 for the varicose veins group vs 0.28 for the control group per 1,000 person-years [793 vs 451 cases]; ARD, 0.20 [95% CI, 0.16-0.24]), and for PAD (10.73 for the varicose veins group vs 6.22 for the control group per 1,000 person-years [16,615 vs 9,709 cases]; ARD, 4.51 [95% CI, 4.31-4.71]). The hazard ratios for the varicose veins group compared with the control group were 5.30 (95% CI, 5.05-5.56) for DVT, 1.73 (95% CI, 1.54-1.94) for PE, and 1.72 (95% CI, 1.68-1.77) for PAD.

The study used insurance claims data that do not include information on patients who do not seek medical care, therefore the researchers said that the findings may apply only to risk among patients with more severe varicose veins who needed medical attention.

"Not much is known about varicose veins and the risk for these other diseases," said Chang. "Elucidating potential associations between varicose veins and health-threatening diseases is important."